Help needed to understand error message.

[Philipp Thomas]

I'm patching a Makefile.am and am thus calling autoreconf to regen the
Makefile.in. Unfortunately the configure.ac is doing advanced autoconf/m4
stuff that I don't quite understand.

configure.ac at the top has

###############################################################################
# prelude
###############################################################################

m4_include([project/project.m4sugar])

m4_define([SVNINFO],m4_esyscmd([svn info 2>/dev/null]))

m4_define([PRJ_repo_url],m4_bregexp(SVNINFO,[^URL: *\(.+\)],[\1]))
m4_define([PRJ_repo_root],m4_bregexp(SVNINFO,[^Repository Root: *\(.+\)],[\1]))
m4_define([PRJ_repo_uuid],m4_bregexp(SVNINFO,[^Repository UUID: *\(.+\)],[\1]))
m4_define([PRJ_repo_rev],m4_bregexp(SVNINFO,[^Last Changed Rev: *\(.+\)],[\1]))
m4_define([PRJ_repo_date],m4_bregexp(SVNINFO,[^Last Changed Date: 
*\(.+\)],[\1]))
m4_define([PRJ_repo_type],ifelse(m4_bregexp(PRJ_repo_url,[/releases/]),[-1],[developer],[stable]))

m4_define([PRJ_version_hex],m4_format([0x%04x%02x%02x],PRJ_version_major,PRJ_version_minor,PRJ_version_point))

m4_define([PRJ_snapshot],
    m4_bregexp(m4_esyscmd([(test "$SNAPSHOT" = "1" && date +%Y%m%d) 
2>/dev/null]),[\([0-9]+\)],[\1]))
m4_define([PRJ_repo_type],ifelse(m4_len(PRJ_snapshot),8,[snapshot],PRJ_repo_type))

m4_define([PRJ_version],ifelse(
    
PRJ_repo_type,[stable],m4_format([%d.%d.%d],PRJ_version_major,PRJ_version_minor,PRJ_version_point),
    
PRJ_repo_type,[snapshot],m4_format([%d.%d-%s],PRJ_version_major,PRJ_version_minor,PRJ_snapshot),
    
PRJ_repo_type,[developer],m4_format([%d.%d-r%d],PRJ_version_major,PRJ_version_minor,PRJ_repo_rev),
    m4_format([%d.%d-r%d],PRJ_version_major,PRJ_version_minor,PRJ_repo_rev)))

And the included project.m4sugar is:

dnl
dnl This file defines highest-level project meta-data in autoconf M4 format.
dnl It is needed downstream by configure.ac.
dnl
define([PRJ_name],           [MP4v2])
define([PRJ_name_lower],     [mp4v2])
define([PRJ_name_upper],     [MP4V2])
define([PRJ_url_website],    [http://code.google.com/p/mp4v2])
define([PRJ_url_downloads],  [http://code.google.com/p/mp4v2/downloads/list])
define([PRJ_url_discussion], [http://groups.google.com/group/mp4v2])
define([PRJ_irc],            [irc://irc.freenode.net/mp4v2])
define([PRJ_bugreport],      address@hidden)
define([PRJ_version_major],  [1])
define([PRJ_version_minor],  [9])
define([PRJ_version_point],  [1])

Autoconf 2.68 reports:

/usr/bin/m4:configure.ac:25: empty string treated as 0
/usr/bin/m4:configure.ac:26: empty string treated as 0

Coould somebody please help me understanding what is going wrong so that I
might fix the sources?

Philipp